Wan You-bao, Yuan Guo-xiang, Wu Yu-rong, Yang Pei-zhi, Xin San-fa, Zhu Hai-bin, Huang Xue-jun, Yang Hui
Institution of Inorganic Material, College of Material and Biology, Zhejiang University, Hangzhou 310027, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2007 Feb;27(2):287-91.
A batch of potassium lithium niobate (KLN) crystals with different compositions were grown by using TSSG technique. Samples with three different compositions were well polished. By using near infrared cw:Ti-sapphire laser, their Second Harmonic Generation (SHG) properties were investigated. The results showed that the SHG effect is related to the composition of the samples, and their frequency-doubling efficiency enhanced with the raise of Li ions content in the crystal. By using infrared Raman technique, the properties of nonlinear lattice vibration of thee samples were investigated, and the character of Raman spectrum were analyzed, as well the effect of composition on the SHG properties were discussed. The analysis results showed the striking effects of Li content for these Raman peaks. For KLN sample with small Li content, the three character peaks belonged to [NbO6]7- octahedron show simple peak. With the raise of Li content in crystal, the peaks belonged to v2 mode were partly split, and the peak belongs to v5 mode was broadened. When the Li content approach to the chemical composition KLN crystal, and the structure of [NbO6]7- octahedron is almost to be disorganized, the peaks belonged to v5 mode were split, and the peaks belonged to v1 mode and v2 mode were partly split also, with more distinct weak peaks in the wavelength range of 100-400 cm(-1). These effects were caused by the raise of Li content, which leads to the severer aberrance of [NbO6]7- octahedron in KLN crystal, and disturbing the lattice vibration of the octahedron. This phenomenon is agreed with the nonlinear properties of potassium lithium niobate crystal.
采用顶部籽晶溶液生长法（TSSG技术）生长了一批不同成分的铌酸钾锂（KLN）晶体。对三种不同成分的样品进行了精细抛光。利用近红外连续波钛宝石激光器，研究了它们的二次谐波产生（SHG）特性。结果表明，SHG效应与样品成分有关，并且随着晶体中锂离子含量的增加，其倍频效率提高。利用红外拉曼技术，研究了这些样品的非线性晶格振动特性，分析了拉曼光谱特征，并讨论了成分对SHG特性的影响。分析结果表明锂含量对这些拉曼峰有显著影响。对于锂含量较低的KLN样品，属于[NbO6]7-八面体的三个特征峰呈现单峰。随着晶体中锂含量的增加，属于v2模式的峰部分分裂，属于v5模式的峰变宽。当锂含量接近化学计量比的KLN晶体时，[NbO6]7-八面体的结构几乎紊乱，属于v5模式的峰分裂，属于v1模式和v2模式的峰也部分分裂，在100 - 400 cm(-1)波长范围内出现更明显的弱峰。这些效应是由锂含量的增加引起的，这导致KLN晶体中[NbO6]7-八面体的畸变更严重，扰乱了八面体的晶格振动。这种现象与铌酸钾锂晶体的非线性特性相符。
